Shift lever lock system

Abstract

A vehicle immobilizer locks the transmission shift lever in the park position. A key has an identification code and a transmitter. When the key is inserted into a key cylinder and used to rotate the key cylinder to start the vehicle, a code detector reads the key code. The key code is then compared to a prestored key code. If the key codes match, a first detection signal is generated. A brake detector detects when the brake pedal has been depressed and generates a second detection signal. When both the first and second detection signals are generated, the shift lever is unlocked and an engine ECU is enabled so that the engine may be started and the transmission may be engaged.

What is claimed is:  
     
       1. A vehicle immobilizer, comprising: 
       a key rotor having a plurality of rotation positions for receiving a key wherein the key is used to rotate the key rotor;  
       a rotor case for accommodating the key rotor;  
       a shift lever lock mechanism for locking a shift lever; and  
       a detector that detects the rotation positions of the key rotor, wherein the detector unlocks the shift lever with the shift lever lock mechanism when the detector detects that the key rotor is rotated to the plurality of rotation positions in a predetermined sequence, wherein the detector includes:  
       at least one detected member arranged in one of the key rotor and the rotor case;  
       at least one position sensor arranged in the other one of the key rotor and the rotor case to detect the detected member and generate a member detection signal;  
       an ignition switch connected to the key rotor for generating a position signal in accordance with the rotation position of the key rotor;  
       a determination circuit that generates a determination signal when determining that the member detection signal and the position signal have a predetermined relationship; and  
       a controller for unlocking the shift lever with the shift lever lock mechanism when the determination signal is generated and locking the shift lever with the shift lever lock mechanism when the determination signal is not generated.  
     
     
       2. The immobilizer according to  claim 1 , wherein the controller generates a permission signal for enabling starting of the engine when the determination signal is generated. 
     
     
       3. The immobilizer according to  claim 1 , wherein the detector further includes a brake detector that generates a depression signal when a brake pedal is depressed, and wherein the controller unlocks the shift lever when the determination signal and the depression signal are both generated and locks the shift lever when at least one of the determination signal and the depression signal is not generated. 
     
     
       4. The immobilizer according to  claim 3 , wherein the controller generates a permission signal for permitting starting of the engine when the determination signal and the depression signal are both generated. 
     
     
       5. The immobilizer according to  claim 1 , further comprising: 
       a code transmitter incorporated in the key for holding and transmitting a key identification code;  
       a memory that stores a reference identification code that is identical to the key identification code; and  
       an engine drive permission circuit that receives the key identification code from the code transmitter, comparing the key identification code with the reference identification code, and generating a permission signal to enable starting of the engine when the two identification codes match.  
     
     
       6. A vehicle immobilizer, comprising: 
       a key rotor having a plurality of rotation positions for receiving a key wherein the key is used to rotate the key rotor;  
       a rotor case for accommodating the key rotor;  
       a shift lever lock mechanism for locking a shift lever; and  
       a detector that detects the rotation positions of the key rotor, wherein the detector unlocks the shift lever with the shift lever lock mechanism when the detector detects that the key rotor is rotated to the plurality of rotation positions in a predetermined sequence, wherein the detector includes:  
       at least one detected member arranged in one of the key rotor and the rotor case;  
       at least one position sensor arranged in the other one of the key rotor and the rotor case to detect the detected member and generate a member detection signal in accordance with the rotation positions of the key rotor;  
       an ignition switch connected to the key rotor for generating a position signal in accordance with the rotation position of the key rotor;  
       a determination circuit that generates a determination signal when determining that the member detection signal and the position signal vary in a predetermined sequence; and  
       a controller for unlocking the shift lever with the shift lever lock mechanism when the determination signal is generated and locking the shift lever with the shift lever lock mechanism when the determination signal is not generated.